The rapidly growing field of molecular imaging seeks to develop strategies for non-invasively imaging specific gene and protein targets with the goal of better understanding disease initiation and progression in vivo and accelerating the translation of basic knowledge in the biological sciences into new diagnostic and therapeutic approaches in the clinic. This is a highly interdisciplinary research field, involving scientists from the biological, engineering, physical and medical sciences. Recently, many imaging, pharmaceutical and biotechnology companies have set up molecular imaging programs. The most successful programs, whether in academia or industry, will be those in which the diverse fields listed above are well integrated, and which are led by multidisciplinary scientists that are trained in sufficient depth and breadth to generate new ideas and direct the execution of those ideas. The goal of our predoctoral training program is to train the next generation of leaders in the molecular imaging field for both academia and industry. This training program is based in biomedical engineering, a discipline that seeks to seamlessly integrate engineering, biology and medicine. It is a natural home for the imaging science that is the foundation for molecular imaging research. We propose to support six predoctoral students per year with a carefully constructed curriculum that will provide them with fundamental knowledge in engineering, cell & molecular biology, physiology, instrumentation, synthetic chemistry, and mathematics. A course in molecular imaging will take these fundamentals and show students how to apply them to particular biologic questions. Trainees can select from 16 faculty mentors that span the breadth of molecular imaging research topics. In addition, trainees can take 3- month internships to gain industrial experience, participate in a monthly molecular imaging journal club, and attend an international molecular imaging conference to see at first-hand the latest developments in the field and form connections with other scientists working on similar research.